GAINESVILLE, Fla. — As America becomes a nation of caffeinated insomniacs, a new University of Florida study shows lack of sleep not only makes people tired and cranky but also causes them to dislike and even hate their jobs the next morning.

“It’s intuitive that one might feel a little irritable, but to experience emotional spillover to the point of actually feeling less satisfied with work is a little surprising,” said Brent Scott, a UF graduate student assistant in management who led the research.

The effects were most pronounced in women, who reported suffering more fatigue and hostility and being less attentive and happy than their male counterparts, said Scott, whose study is scheduled to be published in the October issue of the Journal of Management.

“These differences may have something to do with society’s expectations for men and women,” he said. “Women are encouraged to be nurturing and more emotionally expressive than men, who have been taught to remain stoic and restrain their emotions.”

Forty-five employees at a Southeastern regional office of a large national insurance company participated in the study, which Scott did with UF management professor Timothy Judge. Every day for three weeks in February 2005, the participants logged onto a Web site and completed a survey at the end of the workday asking them to rate their level of work satisfaction, the extent to which they suffered from sleep problems and how often they experienced certain emotions.

Employees reported higher rates of job satisfaction if they had slept soundly the night before and lower levels if they had experienced insomnia, he said.

Although it is known that sleep restores the body, particularly the brain, it is less understood how it affects emotions and attitudes, Scott said. “Given that most employees spend the majority of their waking hours at work, it’s curious that the effects of lack of sleep have not been examined more thoroughly within the working environment,” he said.

The issue is becoming increasingly important because people are getting less sleep,Scott said. A recent survey by the National Sleep Foundation found that Americans sleep an average of 6.8 hours a night on weekdays, with as many as a quarter reporting sleeping well only a few nights a month, he said.

“Undoubtedly one of the reasons Americans are getting less sleep is the growth in dual-career couples,” he said. “When husbands and wives both work, they come home having to do household duties and take care of children, which leaves them little time for sleep.”

Employers contribute to the problem by making more demands, Scott said. “With employers trying to squeeze every last bit of productivity out of employees and having them work extended hours, a 40-hour week is basically nonexistent anymore in some occupations,” he said.

Employers should pay attention to workers’ needs, though, because lack of sleep may ultimately hurt job performance, Scott said. One of the first changes that might be apparent is employees being less willing to help co-workers who miss work because of illness or another reason, he said.

“They might continue to complete their formal job requirements, but they may not go above and beyond the call of duty to help a co-worker who needs it,” he said.

Companies can address the problem by giving employees flexibility in making their schedules, providing on-site child care and offering wellness programs designed to teach employees how to reduce insomnia, he said.

Individuals can take steps of their own by exercising more and limiting consumption of caffeine and alcohol, he said.

By not doing anything, businesses risk more frequent turnover if their employees are not content in the workplace, Scott said. “We know from other research that people who are dissatisfied with their jobs leave organizations at higher rates than those who are happy and committed to their jobs,” he said.

Jerald Greenberg, a professor of management and human resources at The Ohio State University and an expert on motivation and leadership, said Scott’s research is interesting and important.

“Although managers often complain about employees’ poor job performance, this research suggests that they actually may be responsible for it by creating conditions that lead their employees to suffer insomnia,” Greenberg said. “Hopefully, managers will take note by becoming part of the solution.”